This invention relates to apparatus used for cleaning manufactured parts, and specifically for removing oil from the surfaces thereof by immersing the parts in a container of cleaning liquid maintained in a highly turbulent state. Since this is an on-going cleaning process, the oil must then be removed from the cleaning liquid. In the past, this has been done by drawing the cleaning liquid from the container and processing it, and then returning the liquid to the container for use in future parts cleaning operations. The usual way of processing the contaminated cleaning liquid is to pass it through a filter cartridge which removes the bulk of the oil, but which must be frequently replaced by new cartridges, which is expensive and time consuming.
In view of the fact that the parts being cleaned must be lowered into the agitated liquid and later retrieved by raising them through the surface thereof, the liquid must be sufficiently agitated that the oil can not form a skim on the liquid surface. Otherwise, the cleaned parts would be again contaminated as they are raised through the surface during removal from the container. In prior art apparatus of this type, besides filtering of the liquid during its use, which was not fully effective to keep down the build-up of oil in the container, the apparatus had to be periodically shut down to allow the oil to float to the surface of the liquid and form a skim thereon, which was removed by a skimmer wheel or belt from the surface while the liquid was still quiescent. U.S. Pat. Nos. 4,082,867 and 4,136,217 to Henley show skimmer belts operating in oil recovery tanks which are located separately. Such periodic shutting down of the apparatus is inefficient, and often not done sufficiently frequently.
The prior art shows other ways of removing oil from cleaning liquids. For instance, in U.S. Pat. No. 3,734,776 to Keough the oil is removed by centrifuging; in U.S. Pat. No. 4,162,199 to English the oil is removed by distillation; in U.S. Pat. No. 3,156,248 to Rand it is removed by vaporization; and in U.S. Pat. No. 3,930,879 to Erickson it is removed by separating a proportion of the cleaning liquid from the container and sending it to a gravity separator where the oil separates out and is left behind when the wash water is returned to the container. In U.S. Pat. No. 3,810,786 to Lindgren the oil is likewise separated out in an auxiliary tank with a vertical partition dividing the tank below the floating level of the oil.
In this disclosure the cleaning liquid is an alkaline solution in water, a particular example of which comprises a commercially available product of J. Hall Marketing Company, type 108B which is added to water. Other cleaning products are of course available for substitution instead of the liquid solution just mentioned. The oil being lighter than the solution, it floats to the surface and forms a skim if the solution is relatively quiescent. The high turbulance in the cleaning container is of course very helpful in cleaning the parts placed therein.